CAULANTHUS S. Watson, Bot. U.S. Geol. Survey 40th Parallel 5: 27. 1871.
Ihsan A. Al-Shehbaz
Tribe: Thelypodieae Prantl in Engler & Prantl, Nat. Pflanzenfam. III. 2: 155. 1891.
Name derivation: Greek kaulos, stem, and anthos, flower, in reference to the insertion of flowers along the stem.
Lectotype species: Caulanthus crassicaulis (Torrey) S. Watson (based on Streptanthus crassicaulis Torrey). Typification by Payson (1923: 283).
Guillenia Greene, Leafl. Bot. Observ. Crit. 1: 227. 1906. Type species: G. lasiophylla (W. J. Hooker & Arnott) Greene (based on Turritis lasiophylla W. J. Hooker & Arnott).
Microsisymbrium O. E. Schulz in Engler, Pflanzenreich IV. 105(Heft 86): 159. 1924. Type species: not designated. Generic name illegitimate because it includes the type species of the earlier-published Guillenia.
Stanfordia S. Watson, Geol. Surv. California Bot. 2: 479. 1880. Types species: S. californica S. Watson.
Herbs, annual, biennial or perennial with a woody caudex, usually glaucous. Trichomes absent or simple, very rarely mixed with fewer, stalked, 2-rayed ones. Multicellular glands absent. Stems erect or rarely decumbent, simple or branched above, occasionally inflated. Basal leaves petiolate, rosulate or not, simple, entire, dentate, lobed, or pinnatifid; cauline leaves petiolate or sessile and sagittate, auriculate, or amplexicaul, entire, dentate, or lobed. Racemes corymbose, many flowered, ebracteate or rarely lowermost several flowers bracteate, elongated in fruit, sometimes with a terminal cluster of sterile flowers; rachis straight; fruiting pedicels slender or stout, erect or ascending to divaricate or reflexed. Sepals oblong or ovate to lanceolate, free, often forming an urceolate calyx, erect or rarely spreading, caducous, base of lateral pair saccate or not. Petals yellow, brown, purple, white, or greenish yellow, erect at base with a flaring blade or rarely spreading, longer than sepals; blade linear to oblanceolate, often channeled and crisped or flat, apex obtuse; claw often well differentiated from and sometimes longer and wider than blade, slender to oblanceolate, glabrous, unappendaged, entire. Stamens 6, tetradynamous or in 3 pairs of unequal length, rarely subequal; filaments wingless, unappendaged, glabrous, free or sometime adaxial or both median pairs united; anthers oblong, equal or adaxial pair smaller, obtuse or sometimes apiculate. Nectar glands mostly confluent and subtending bases of all filaments, median glands present. Ovules 24–210 per ovary; placentation parietal. Fruits dehiscent capsular siliques, linear, terete, rarely 4-angled, latiseptate, or angustiseptate, not inflated, unsegmented; valves papery to leathery, usually with a distinct midvein, glabrous or rarely scabrous, not keeled, smooth or sometimes torulose, wingless, unappendaged; gynophore obsolete or to 1.5 mm; replum rounded, visible; septum complete, membranous, veinless; style obsolete or up to 4 mm; stigma entire or 2-lobed, the lobes free, opposite valves or replum, unappendaged. Seeds uniseriate, wingless or rarely margined, oblong to ovate or rarely subglobose, plump or flattened; seed coat minutely reticulate, not mucilaginous when wetted; cotyledons entire or rarely trifid, incumbent or obliquely so. n = 14.
Seventeen species: W United States, NW Mexico.
References: Al-Shehbaz (1973), Buck (1995), Payson (1923), Pepper & Norwood (2001).
See interactive key to the species